Noninvasive measurement of regional cerebral blood flow will be continued and compared in normal volunteers, in subjects without brain disease but with risk factors for cerebral arteriosclerosis (hypertension, diabetes, hyperlipidemia) and in patients with cerebrovascular disorders including: transient ischemic attacks, cerebral infarction, subarachnoid and intracranial hemorrhage, multi-infarct and related dementias, migraine and vascular headaches. The effects of activation procedures, including different types of brain work, changes in respiratory rate and manipulation of blood pressure will be compared in normals, those with risk factors and the patient population. The mechanism of diaschisis will be examined in the baboon and gerbil models, with application of new methods for measuring brain stem and cerebellar blood flow already applied to man. Cerebral metabolism, cation movement and neurotransmitter changes with unilateral cerebral infarction will be measured before and after corpus callosum section. Detailed correlation of higher cortical functions will be made in patients with stroke by automated self-assessment devices as well as by conventional psychological test batteries. Innovative methods of 3 dimensional computer analysis of CT scans in stroke will be continued. The effects of various types of stroke on the stages of the sleep-wake cycle will be further assessed and the basic disorder of lipid metabolism underlying cerebral atherogenesis will be further explored.